Uncontrollable crash

[MikeyOnline]

Once the barometer sensor reads the A/C has stopped downward movement by stick control, the A/C will then be able to be shut down by the left stick in the full down position.

One thing I've been wanting to mention and keep forgetting. About a week ago I was hand catching at the end of my flight. Just as I caught it, I felt a stinging on my right leg so I looked down and realized I had been stung by a paper wasp. No big deal but I was now full down on the left stick and waiting for the motors to turn off while stomping my right leg and flailing about a bit to try to shake the wasp off my leg. It took a lot longer than 3 seconds for the motors to turn off even though I was concentrating on my left thumb to be sure I didn't let it up: was full down the whole time because I knew the sooner I could get the motors off, the sooner I could tend to the situation. They only turned off once I had shaken the wasp off my leg and was standing still again, so it made me wonder if maybe it's even more sophisticated than just a descent reading. It seemed like it wanted the AC to be "still" for a bit before it turned the motors off. Is it possible that it looks at the IMU as well to be sure it is stable before cutting the motors? I've been meaning to test it again by moving the AC around after I catch it to see if it refuses to cut the motors until I steady my hand but I always forget. It would make sense that it'd look for the craft to be stable and that would greatly reduce the likelihood of it shutting off mid air even if there was some sort of weird updraft: it'd still be tilting around.

Mike

 

[MrGarvey]

VRS as the above prior poster said is very dangerous for copters. When descending straight down you may notice a wobbling...This is VRS. This was the reason one of the choppers went down in the raid on Bin Laden's compound. The VRS was aggravated by the high walls where they were trying to land. The pilot said he just started a rapid descent which he recognized as VRS and managed to move enough in the tight quarters and partially got out of it. He still crashed but it regained enough lift for a "softer" crash keeping everyone on board from dying or being paralyzed from compression of their vertebra. If I'm very high I usually do a spiral descent so that isn't an issue. Even though DJI lowered the max descent rate an updraft could still initiate it.

Thank you for this. I didn't know this was a possibility.

I'll keep this in mind next time I'm flying. You may have saved me a few hundred dollars in heartache. Thanks!

 

[DrDrone413]

I skimmed thru this thread, but didn't see this question.. If someone accidentally performs a CSC mid air as in this case, can they restart the rotors and fly again while falling?? And no... I'm not up for trying that out myself!

And OP... Sorry about your bird. Thanks for helping us become more aware.

 

[Phantom George]

The thing is, is that YOU always fly from 100% down to 30% or whatever EVERY time you go out to fly. It flys just the same from 100% down to 30% or lower just fine. So, DJI may recommend starting with a freshly charged battery but it flys the same taking it up for a couple of laps starting at 70% or 50%. YOU JUST HAVE SHORTER FLIGHT TIMES.


Sent from my iPhone using PhantomPilots mobile app

In my experience it's not so️
Starting with a fully charged battery never shows up with a critical or below 3.6V drop. But if I start with 70, or 50 or 60% charged battery, I see invariably on full stick movements a voltage drop into the yellow and or even red voltage.
My conclusion is start with a full battery charge is different to a partly charged battery.

 

[YCampCub]

Is VRS more prone with prop guards?

 

[flyNfrank]

One thing I've been wanting to mention and keep forgetting. About a week ago I was hand catching at the end of my flight. Just as I caught it, I felt a stinging on my right leg so I looked down and realized I had been stung by a paper wasp. No big deal but I was now full down on the left stick and waiting for the motors to turn off while stomping my right leg and flailing about a bit to try to shake the wasp off my leg. It took a lot longer than 3 seconds for the motors to turn off even though I was concentrating on my left thumb to be sure I didn't let it up: was full down the whole time because I knew the sooner I could get the motors off, the sooner I could tend to the situation. They only turned off once I had shaken the wasp off my leg and was standing still again, so it made me wonder if maybe it's even more sophisticated than just a descent reading. It seemed like it wanted the AC to be "still" for a bit before it turned the motors off. Is it possible that it looks at the IMU as well to be sure it is stable before cutting the motors? I've been meaning to test it again by moving the AC around after I catch it to see if it refuses to cut the motors until I steady my hand but I always forget. It would make sense that it'd look for the craft to be stable and that would greatly reduce the likelihood of it shutting off mid air even if there was some sort of weird updraft: it'd still be tilting around.

Mike

We need to keep in mind that dji has not catered to Hand Catching in anyway on the P3. If the sensor is reading the A/C is still displaying erratic movement, then as a precaution it might be setup to continue to remain live. As we know, it was never programmed based on being held in the pilots hand.

Btw, all my return flights land on a soft rubber pad that absorbs hard contact really well. Only in a emergency would I land my A/C on the ground, grass, concrete, ect. I take all debre types out of the possibility of causing any kind of issue.

 

[FLyAgaric421]

Definitive Fact: Holding left stick all the way down WILL NOT shut off your motors while in flight. I do it literally every time I fly..

 

[Start Visit]

I am 100% sure. Only one stick is required. I personally think its silly.

i use one left stick down all the times on fast descent. motors working fine. V combination hold will shut motors down.

 

[Multicoptertec]

I commonly use full left stick down to descend from high altitudes. Did just that with a group of flyers this past weekend. I can assure you, as others have here, that the motors will not shut down. I do not hand catch, but always land manually, and then hold left stick down to kill the motors. Once this weekend, I thought I held left stick down long enough, only to walk over to the bird and find the motors still going. As far as batteries, I flew through 4 batteries, landing and then taking off again with batteries as low as 40%, and had no issues at all.